Such liquid droplet spray devices are also sometimes called “piezoelectric spray devices,” “aerosol generators,” “nebulizers” and the like. They normally contain a nozzle body on a support part, in particular, a nozzle body of a liquid droplet spray device, which dispenses a liquid substance as a liquid droplet spray. They further generally consist of an ultrasound generating means, such as a piezoelectric actuator for causing the liquid to vibrate so as to be accelerated and expelled as droplets through outlet nozzles provided in the nozzle body. The device may further consist of elements such as a liquid space, a liquid feed and a fluid interface linked to a reservoir, as well as electrical connections between the ultrasound generating means and a corresponding electronic circuitry. The liquid may be, for example, an ambient fragrance, a perfume, an insecticide, an aromatherapy essence, a liquid pharmaceutical formulation, aqueous based liquids and flammable or combustible liquids.
Such nozzle bodies of a liquid droplet spray device are sometimes called “aperture plates,” “nozzle arrays,” “dosing aperture,” “orifice plate,” “vibratable membrane member,” “dosing aperture arrangement,” “aerosol generator,” and the like. These terms are hence to be understood as being interchangeable throughout the present document.
In fact, such nozzle bodies and droplet spray devices are well known, for example see the document EP 1 129 741 in the name of the present Applicant. This document describes a liquid droplet spray device having a top substrate formed of a main body and of a nozzle body. The nozzle body contains a nozzle array of liquid droplet outlet means allowing a liquid substance contained in the liquid droplet spray device to exit the device, in this case, as a spray of droplets. A piezoelectric actuator is used to cause the liquid to undergo a vibration so as to generate the droplet spray.
It is well known to disperse fragrances and insecticides into the atmosphere by such a device to form a mist or cloud of small droplets of a liquid substance containing the fragrance or insecticide, and to eject the mist or cloud into the atmosphere in the form of minute liquid droplets. As the mist or cloud settles, the fragrance or insecticide evaporates from the droplets. Examples of devices for doing this are shown in U.S. Pat. Nos. 4,085,893, 5,173,274, 5,601,235 and 5,894,001. In general, these devices supply the liquid fragrance or insecticide to a vibrating atomization plate which, due to its vibrations, breaks up the liquid into fine droplets and ejects them upwardly in the form of a mist or a cloud. As the droplets fall back down, the fragrance or insecticide evaporates from the droplets and disperses into the atmosphere.
However, the conventional devices expel clouds of droplets where the density of the expelled cloud may be quite high, thereby resulting in droplets falling back down before being evaporated due to the fact that droplets “stick” to each other. In fact, such sticking leads to larger droplets that take longer to evaporate before falling back due to gravity.
It is, therefore, an object of the present invention to provide an innovative nozzle body and corresponding liquid droplet spray device for controlling the evaporation of the droplet cloud resulting from nebulising a liquid that overcomes the inconveniences and limitations presented by the prior art documents, and that allows it to minimise the fall back for expelled liquids.